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A computer-controlled LED display system including an N×M rectangular array of light units. Each light unit includes one or more LED\s that are driven so as to emit a train of light pulses separated by intervals of substantially zero light intensity. The temperature of the LED cathodes will decrease

A computer-controlled LED display system including an N×M rectangular array of light units. Each light unit includes one or more LED\s that are driven so as to emit a train of light pulses separated by intervals of substantially zero light intensity. The temperature of the LED cathodes will decrease during each interval of zero emitted light intensity, so that the average temperature of each LED over its operating period will be less thaN it would be with zero intensity intervals of shorter duration. In a preferred embodiment, the drive circuit has a nonzero, finite RC constant and a capacitor connected in series with the LED\s, so as to produce sufficiently long duration, substantially zero intensity intervals between the emitted light pulses. Each LED driving circuit includes a switch (preferably of the opto-coupler or triac type) for switching the circuit between “on”and “off”modes. Each switch is controlled by serial digital signals supplied via an interface unit. The interface unit includes a serial-to-parallel converter and a parallel-in-parallel-out shift register for each of the M columns of the light unit array. Each serial-to-parallel converter-shift register pair accepts serial digital control pulses and generates N parallel data streams, each controlling one of the N light units in the Mth array column.

대표청구항 ▼

A display system, including: at least one LED; a drive circuit having a finite, nonzero RC time constant, including a capacitor connected in series with the at least one LED, and capable of driving the at least one LED into a light-emitting mode in response to an alternating voltage signal, in which

A display system, including: at least one LED; a drive circuit having a finite, nonzero RC time constant, including a capacitor connected in series with the at least one LED, and capable of driving the at least one LED into a light-emitting mode in response to an alternating voltage signal, in which light-emitting mode each driven LED emits a train of light pulses separated by intervals of substantially zero light intensity, and in which light-emitting mode the drive circuit introduces a phase shift between the alternating voltage signal and the current through each driven LED to increase the duration of the substantially zero light intensity intervals beyond the duration said intervals would have if the capacitance of the drive circuit were zero, so as to reduce the average temperature of each LED in the light emitting mode below the average temperature each said LED would have if the capacitance of the drive circuit were zero; a switch coupled with the drive circuit, and capable of switching in response to control signals between an on position in which the alternating voltage signal is supplied through the switch to the drive circuit, and an off position preventing the alternating voltage signal from propagating through the switch to the drive circuit; and a drive controller coupled to the switch, for generating control signals and supplying said control signals to said switch, wherein each of the control signals coincides with a zero crossing of the alternating voltage signal.